OK for these next set of questions I am supposed to say whether or not the following equations are linear. my text gives this formula that I am supposed to match the equation with..I don't know I'm not getting it all the way.
well here are the equations..
1. (y''')^2 - 5y' +2y = x^(19)
2. (tan x)y'' + (sin x)^2*y' + (cos x)y = 0
3. x^2*y'' - xy' + 5y^2 = 18
1. This one is of the 3rd order and not linear, because there is no p(x)y term
2. i said this was linear and its of the second order
3. this is of the second order but not linear because there is no q(x) term.
i think the way i looked at these problems is not quite correct, so any help would be appreciated. thanks in advance
oh and the * means multiplication. thanks